This invention relates to an emulsion ink of a water-in-oil (w/o) type useful for stencil printing.
In stencil printing, an ink is applied onto a perforated stencil master backed by a printing paper and is passed through the perforations to form an image on the printing paper. Since a pattern of an emulsion ink printed on a paper is dried through evaporation and penetration thereof, fixation property of the ink is one of the very important aspect of the emulsion ink for stencil printing. It is also important that the ink should not be solidified before being applied onto a paper. It is also desired that the ink should no emit an unpleasant odor.
In necessitating saving of paper consumption, there is an increasing demand for a w/o type ink adapted for both sides printing. In both sides printing, a reverse side of a recording paper is printed after a front side has been printed. Thus, it is desired that the printed ink be quickly dried, since otherwise the ink is apt to transfer onto feed rolls of a printing machine to cause fouling of recording papers.
Known w/o type emulsion ink, however, is not satisfactory in these points.
For example, JP-A-6-107998 discloses a w/o type emulsion ink containing a liquid alkyd resin and a solvent containing a small aromatic compound content. This ink has a problem because the solvent is volatile in nature. Thus, when the printer containing the ink is maintained unused for a few months, the ink is dried to cause clogging of the screen.
JP-A-9-268268 and JP-A-9-31384 disclose a w/o type emulsion ink using a motor oil. The ink has a problem because the motor oil emits an unpleasant odor and because the viscosity of the motor oil significantly varies with the temperature.